Grafana - parse error: missing unit character in duration

Trying to setup alerts for Zenduty. Got this error in Grafana:

lvl=eror msg="Alert Rule Result Error" logger=alerting.evalContext ruleId=36 name="Http Response Code alert" error="1:89: parse error: missing unit character in duration: " changing state to=keep_state

Is something missing somewhere in duration?

Found, this seems to be due to this:
https://github.com/grafana/grafana/issues/15168
we too use $__interval as best practice, so those alert are useless?